Re: [PATCH 01/20] mtd: rawnand: txx9ndfmc: Mark driver struct with __refdata to prevent section mismatch warning

From: Miquel Raynal <miquel.raynal@bootlin.com>
To: "Arnd Bergmann" <arnd@arndb.de>
Cc: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	"Masahiro Yamada" <masahiroy@kernel.org>,
	"David Woodhouse" <dwmw2@infradead.org>,
	linux-kbuild@vger.kernel.org,
	"Richard Weinberger" <richard@nod.at>,
	"Atsushi Nemoto" <anemo@mba.ocn.ne.jp>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	linux-mtd@lists.infradead.org,
	"Pengutronix Kernel Team" <kernel@pengutronix.de>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Vignesh Raghavendra" <vigneshr@ti.com>
Subject: Re: [PATCH 01/20] mtd: rawnand: txx9ndfmc: Mark driver struct with __refdata to prevent section mismatch warning
Date: Mon, 9 Oct 2023 15:37:41 +0200	[thread overview]
Message-ID: <20231009153741.5b04a137@xps-13> (raw)
In-Reply-To: <55a03e14-7a92-4cf0-82d4-5cbde64d69db@app.fastmail.com>

Hi Arnd,

arnd@arndb.de wrote on Mon, 09 Oct 2023 15:01:17 +0200:

> On Mon, Oct 9, 2023, at 14:46, Miquel Raynal wrote:
> >> On Mon, Oct 09, 2023 at 10:43:46AM +0200, Arnd Bergmann wrote:  
> >> > On Mon, Oct 9, 2023, at 09:22, Masahiro Yamada wrote:    
> >> > > On Mon, Oct 9, 2023 at 5:02 AM Uwe Kleine-König <u.kleine-koenig@pengutronix.de> > Can we instead question the use of module_platform_driver_probe()?  
> > I don't have the history in mind, but why not just switch to regular
> > module_platform_driver() registration instead? It seems like the
> > original authors just did not care about the remove path and were
> > happy to skip its implementation.
> >
> > On mtd devices one can argue that the flash underlying stores the
> > rootfs and thus cannot be removed, but I believe today this is a
> > questionable (software) design.  
> 
> It was changed to module_platform_driver_probe() in commit
> 3a2a13fa902d2 ("mtd: txx9ndfmc: use module_platform_driver_probe()")
> with a short changelog text:
> 
> commit 3a2a13fa902d232a1e56582647aed6cb2591349b
> Author: Jingoo Han <jg1.han@samsung.com>
> Date:   Tue Mar 5 13:31:24 2013 +0900
> 
>     mtd: txx9ndfmc: use module_platform_driver_probe()
>     
>     This patch uses module_platform_driver_probe() macro which makes
>     the code smaller and simpler.
>     
>     Signed-off-by: Jingoo Han <jg1.han@samsung.com>
>     Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
>     Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
> 
> Instead of just simplifying the code, I think that was actually
> a bugfix because it prevented both the probe and remove callbacks
> from getting called after getting dropped (deferred probe or
> unbind/rebind). Using module_platform_driver() is probably
> even better here, but then we need to remove both the __init
> and __exit annotations.

Agreed.

Thanks,
Miquèl